more doc

devices/belkin-rt3200/default.nix

@@ -1,4 +1,4 @@
-{
+rec {
   description = ''
     Belkin RT-3200 / Linksys E8450
     ******************************
@@ -17,6 +17,7 @@
     - b/g/n wireless using MediaTek MT7622BV (MT7615E driver)
     - a/n/ac/ax wireless using  MediaTek MT7915E
   '';
+  installer = "ubimage";
 
   system = {
     crossSystem = {
@@ -160,7 +161,7 @@
           maxLEBcount = "1024"; # guessing
         };
 
-        defaultOutput = "ubimage";
+        defaultOutput = installer;
         # the kernel expects this to be on a 2MB boundary. U-Boot
         # (I don't know why) has a default of 0x41080000, which isn't.
         # We put it at the 32MB mark so that tftpboot can put its rootfs